Montaging of fundus images can aid clinicians by providing a more complete view of the retina. Fundus image montaging is a common technique for extending the imaged field-of-view, and has been offered as a feature on fundus cameras, including the Zeiss VISUCAM® and Heidelberg SPECTRALIS®. Wide-field fundus images (e.g. greater than 45 degrees field of view) are particularly affected by the inherent spherical-to-planar projection during retinal imaging, which results in apparent distortion that makes collating the images into a single mosaic challenging.
Some of the prior-methods (see for example Lee, Sangyeol, Michael D. Abramoff, and Joseph M. Reinhardt. “Feature-based pairwise retinal image registration by radial distortion correction,” Medical Imaging. International Society for Optics and Photonics, 2007; Can, Ali, et al, “A feature-based, robust, hierarchical algorithm for registering pairs of images of the curved human retina.” Pattern Analysis and Machine Intelligence, IEEE Transactions on 24.3 (2002): 347-364; and Can, Ali, et al. “A feature-based technique for joint, linear estimation of high-order image-to-mosaic transformations: Mosaicing the curved human retina.” Pattern Analysis and Machine Intelligence, IEEE Transactions on 24.3 (2002): 412-419, each of which are hereby incorporated by reference) describe ways of applying distortion correction to fundus images in order to improve stitching performance.
In general photography, especially outdoor photography, montaging of panoramic mosaics is performed with consideration of three-dimensional geometry (see for example Brown, Matthew, and David G. Lowe. “Automatic panoramic image stitching using invariant features.” International journal of computer vision 74, no. 1 (2007): 59-73). Distortion of the camera is considered in this field, but not with particular regard to the optics of the eye.
Here, we present a new technique for creating a panoramic montaged image of two or more wide-field fundus images of an eye while correcting for projection distortion(s) inherent to an imaging system.